Special Counsel Robert Mueller just got Paul Manafort sent to prison for life, and he’s just revealed in a court filing that he has proof Roger Stone was conspiring with Russian government hackers during the election. All that’s left to do, really, is to take down Donald Trump. That’s why it’s such a big deal that, according to several major news outlets today, Mueller is now subpoenaing the former director of Cambridge Analytica.

The case against Roger Stone alone is enough to prove that there was a criminal plot between the Trump campaign and the Kremlin to alter the outcome of the 2016 election. But while that’s damaging and humiliating to Donald Trump, it doesn’t prove that he was in on the Stone-Russia election rigging scheme. We all instinctively “know” that Stone was running all of this past Trump during their frequent phone calls, but that’s not legal proof. However, a data factory like Cambridge Analytica is dripping with proof.

Donald Trump will try to paint his old friend Roger Stone as having acted as a lone wolf in criminally conspiring with the Kremlin. He’ll claim he had no idea Stone was working with the Putin regime to rig the election. He’ll insist he would have won anyway, even without Stone’s and Putin’s help. But based on the mountain of publicly visible circumstantial evidence alone, Trump-Russia was clearly not a one-off between Stone and the Kremlin.

Cambridge Analytica is widely suspected of having taken voter registration data that was stolen by Russian hackers, and having used it to plot out Donald Trump’s voter targeting strategy. If this can be proven, it’ll demonstrate that the entirety of the Trump campaign was based around what the Russians were cooking up. It’ll prove, either in the court of law or the court of public opinion or both, that Donald Trump was at the center of his campaign’s criminal election rigging conspiracy with the Kremlin. On a different but equally important note, this should also prove that the Kremlin rigged the Brexit vote as well.